when a VM "x" previously used in the system becomes external (as a result of a problem, unclean host removal, etc) it is imported as "external-x". Then if I again create a brand new VM "x" without removing "external-x" and the same situation happens, engine will try to add "external-x" again since IDs are different, only to fail miserably on a name conflict. we should have some protection for these cases. Moreover I think when I name my regular VM as "external-x" I'm going to have the same trouble
The bug was not addressed in time for 4.1. Postponing to 4.2
This will not make it in a reasonable time. Please re-open if you still feel this should be fixed